1. Field of the Invention
The present invention relates to a vehicle interior light mounted in a ceiling or the like in the interior of a vehicle such as an automobile. More particularly, the invention relates to a vehicle interior light including both functions as a lighting for interior illumination and a lighting for decorative interior illumination, wherein, when it functions as the decorative lighting, the light source for the lighting can be controlled with one switch in sync with the light source for the decorative lighting, and the light is lit up with low illuminance (low illumination intensity).
2. Description of the Related Art
Vehicle interior lights having both functions of illuminating the vehicle interior with high illuminance and of illuminating with low illuminance have been conventionally known. A vehicle interior light of this type, for example, having a plurality of lighting LEDs and one night-light LED, is known (refer to Related Art 1, for example). This vehicle interior light provides high-illuminance illumination light by turning on the plurality of room lamp LEDs, as well as low-illuminance dim light by turning on the single night-light LED alone.
Another known vehicle interior light has only one bulb, for example, wherein turning on the lighting switch provides high-intensity illuminating (high illuminance), while turning on a door/light sync switch initiates power supply to the bulb via a resistor element upon the door being opened so as to provide low-intensity illuminating (low illuminance) (refer to Related Art 2, for example). In this vehicle interior light, the illuminance is changed by switching the electrical current applied to the single bulb.
In recent years, vehicle interior lights having a decorative lighting function that provides decorative illuminating with low illuminance, using LEDs or the like as the lighting source, in addition to the high-illuminance room lamp function, have been developed. This decorative lighting function is for improving the lighting design, for example, by emitting light of a different color than that of the room lamp.    [Related Art 1] Japanese Patent Laid-open Publication No. 2004-322860    [Related Art 2] Japanese Patent Laid-open Publication No. 2004-182012
However, with the above-mentioned vehicle interior light having the decorative lighting function, the lighting and decorative lighting are separately controlled, and so the system as a whole cannot be said to have an integral decorative lighting function.
It is conceivable that the above-mentioned vehicle interior light having a plurality of room lamp LEDs and one night-light LED could simply be combined with the vehicle interior light having the decorative lighting function. Even in this case, however, as the circuits for high-intensity illuminating, low-intensity illuminating, and decorative illuminating would be separately provided and not in sync with each other, switches would need to be separately operated, which is troublesome and poorly operable.
It is also conceivable that the above-mentioned vehicle interior light having only one bulb wherein high-illuminance and low-illuminance are switched over using the lighting switch and door/light sync switch could simply be combined with the vehicle interior light having the decorative lighting function. However, in this case, too, the lighting function and decorative lighting function would be configured by separate circuits, so that two or more switches need to be operated for the decorative lighting, resulting in poor operability. Moreover, the low-intensity illuminating is provided only when the door/light sync switch has been turned on and the door is opened, so the usability is poor, because the low-intensity illuminating is not provided at any given time such as during driving at night.